[Help Needed] NAD 2200 or Adcom 545 [Archive]

anonymouse

12-31-2008, 02:02 PM

Are any of the other NAD amps common ground?

I do not know. The 2200PE is a very interesting beast. It has an innovative power supply. Because both channels share the same power supply, they invert one channel's input so that when a massive peak demand exists e.g. a bass intensive kick, both halves of the power (+ve and -ve) are working, rather than one side only. At the outputs, one channel is also inverted.

Another way to look at the output is that if you have a multimeter, you will see that one ground is connected to the positive on the other channel. Now will this work with SDA's? It might, *but*
1) make *very, very sure* that the SDA cable you are using does not connect the two grounds together.
2) Because there is a connection between the two channels in the amp (they both share the same power supply) , the SDA effect *might* still work.

BigMac

12-31-2008, 02:43 PM

Found this looking for an answer to the common ground issue.

http://www.polkaudio.com/forums/archive/index.php/t-25249.html

sdabeliever

12-31-2008, 11:59 PM

Uuhhhmmmmm. I bought the NAD today for $200. was that a mistake? I'm hearing you guys say this may not work. correct? please say it's not true!!

sdabeliever

01-01-2009, 12:02 AM

Now will this work with SDA's? It might, *but*
1) make *very, very sure* that the SDA cable you are using does not connect the two grounds together.

what do you mean?

anonymouse

01-01-2009, 12:12 AM

Do you have a multimeter? If so, hook up the amp, to the speakers, connect the SDA cable, but do not power it on. Check the ohm resistance between the two black terminals on the amp. If the reading is zero (or almost zero), then disconnect the SDA cable. You will need to build a new SDA cable which does not connect the common ground.

sdabeliever

01-01-2009, 12:18 AM

sorry for the noob question ....How do I build that cable? (where do I look for the info? )

also does this mean in the meanwhile I can disconnect the SDA cable and use the 2200pe?

anonymouse

01-01-2009, 12:20 AM

What model of SDA's do you have? Is it a blade-blade or a pin-blade?

And yes in the meantime, it is safe to disconnect the cable and use the 2200

sdabeliever

01-01-2009, 12:25 AM

sda 2 with the blade blade
..

sweet!

anonymouse

01-01-2009, 12:29 AM

To be honest, I'm not sure whether the blade-blade type shorts out the grounds. Others will need to chime in on this. Get a multimeter for $10 at the hardware store or $3 at Harbor Freight and do the test I suggested before you worry further.

sdabeliever

01-01-2009, 12:31 AM

will do. Thank you...It'll be a couple of days b4 I get the amp.

sdabeliever

01-08-2009, 10:06 PM

And you're right. it is boss. It honestly puts our onko m504 to shame : (

anonymouse RE: the OHM's I hooked up a multimeter as you suggested.. everything hooked up with the sda cable connected and nothing turned on. OHMs are about 1/3 of an ohm at the two negative terminals.

I also hooked up our M504 and got the same reading...?

so is a 1/3 of an ohm bad?

sdabeliever

01-09-2009, 12:03 AM

I couldn't edit for some reason...

so another way to ask the question is. Does a reading of 1/3 ohm indicate common ground or non common ground?

I'm getting the same reading when the onkyo m504 and we've had that hooked up to my father in laws 2.3's for a year.

anonymouse

01-09-2009, 12:28 AM

It would appear to me that the interconnect is shorting out the grounds. I would _not_ advise you to use that interconnect.

What is the ohm reading without the interconnect between the two negative terminals at the amp?

sdabeliever

01-09-2009, 12:47 AM

It's exactly the same with SDA cable or without and with either amp.

I tried both set ups on my father in laws' 2.3's and got the same results= ~1/3 ohm

anonymouse

01-09-2009, 01:59 AM

Ok, heres what I want you to do - disconnect the speaker cables from the amp. Measure the resistance between the negative speaker cables (the disconnected cables), with and without the interconnect and report your results

sdabeliever

01-09-2009, 10:18 AM

OK. 1/3 OHM with the sda cable connected on my SDA 2's VS. "off the chart" disconnected. (all the way at the other end of the gauge.)

sdabeliever

01-09-2009, 01:27 PM

heiney9

01-09-2009, 03:49 PM

UPDATE:

my multi meter was not zeroed correctly. It's 1/3 of an ohm off.

I called my local stereo expert and he said the opposite of what you guys are saying. That if it reads zero that it is a common ground amp and that it's fine to use.

??

Reread post #12.................that's what was said. If it reads 0 or close to it then it's common ground and safe to use. The SDA cable has nothing to do with your measurements. You are measuring at the receiver or amplifer's speaker terminals. Power off and speakers disconnected. And as an extra precaution power cord UNPLUGGED.

H9

anonymouse

01-09-2009, 04:57 PM

OK. 1/3 OHM with the sda cable connected on my SDA 2's VS. "off the chart" disconnected. (all the way at the other end of the gauge.)

Ok, your SDA cable is forcing the common ground then. I do _not_ advise you to use this cable with that amp. The amp is not common ground. Your SDA cable is assuming it is common ground and will likely destroy one channel if you use it.

Your best bet is to source of build an A1 interconnect if you want to use that amp with those SDA's.

If you want to check what I am saying, ensure the amp is unplugged, and measure the resistance between the negative on one channel and the negative on the other channel. What you will find is that the resistance is nearly zero from the negative of one channel and the POSITIVE on the other channel, proving conclusively that this amp is not common ground. If it were common ground, the two negative terminals on the amp, with nothing connected should be common at zero resistance.

sdabeliever

01-09-2009, 11:52 PM

Sorry guys I don't seem to be getting this. I know how to use a multimeter but have no idea how this common ground/ non common ground thing works electrically in regards to resistance..hence my confusion.

anonymouse:
I just did this last test and the results are as follows. (with the amp unplugged from the wall) I measured the resistance (the speaker wires were still hooked up) at the two black terminals on the amp= zero ohms. Also measured resistance between black on left and red on right=zero ohms.

You are saying this conclusively proves that it is a NON common ground amp...correct?
If so can you or someone please help me find how to build the A1 sda cable with a transformer (I've only been able to find mention of it on the forum so far)

Heiney9:
I must be misunderstanding what you wrote because to me you and anonymouse are saying the opposite. you said: "If it reads 0 or close to it then it's common ground and safe to use." Anonymouse just said: "What you will find is that the resistance is nearly zero from the negative of one channel and the POSITIVE on the other channel, proving conclusively that this amp is not common ground."

i just want to understand the bottom line not be a pain.

anonymouse

01-10-2009, 12:14 AM

A common ground amp simply means that the left and right channel share a common ground inside the amp. The NAD2200PE does not have the left and right channel grounds connected internally. Therefore it is not common ground.

There are posts on here describing how to build the A1. Honestly though, your best bet would be to sell this amp and buy an Adcom or similar common ground amp. The A1 cable does not give you as good an SDA effect, and you will spend at near $100 building that cable.

sdabeliever

01-10-2009, 12:57 AM

Thanks. sad news. nice amp :(

would it be cheaper to alter the cable I have? Do I need anything other than a transformer to do this? I'll lose at least $50 (shipping paid) on this amp if I turn around and sell it.

Kex

01-10-2009, 01:22 AM

... The 2200PE is a very interesting beast. It has an innovative power supply. Because both channels share the same power supply, they invert one channel's input so that when a massive peak demand exists e.g. a bass intensive kick, both halves of the power (+ve and -ve) are working, rather than one side only. At the outputs, one channel is also inverted. ...
Is that what they call "Power Drive" technology, or is that something different entirely? A fairly recent review of the T955 highlighted this feature, and I'm just curious if it's useful, or if it's useless marketing blurb.

Sorry to derail, slightly, sdabeliever.

daboyz

01-10-2009, 01:39 AM

I wish I would've posted earlier,don't know if it would've mattered but the Adcom 545 is one helluva amp.

heiney9

01-10-2009, 01:45 AM

I wish I would've posted earlier,don't know if it would've mattered but the Adcom 545 is one helluva amp.

Yeah Dave it is, but Adcom gets very little respect here on CP. I've been an advocate for awhile...................but it falls on deaf ears. I'm done speaking of my 20 years of experience with Adcom because..............well ADCOM SUCKS!!! Just ask most people here.

To the OP, sorry if I confused you. Do a search for "common ground" and you should find plenty. I've always understood a common ground amp to read close to zero when using a meter measuring the negative speaker terminals on the amp or receiver.

Good luck on your quest

H9

P.s. FAAAAAAAAAAAAAAK Emotiva is the shiznit and is the best you can buy.............just look at all the threads :rolleyes:

heiney9

01-10-2009, 02:00 AM

The only time (it seems) Adcom gets more than an indifferent review is if one is FS..............then the seller can't say enough positives about their virtues.

I can think of a couple hypocritical sales ;).

H9

daboyz

01-10-2009, 02:09 AM

We'll just keep it our little secret. But, I'll tell you it drives my SDA's very well and as soon as those Lsi9's get here the first amp they'll be hooked up to is the 545.

heiney9

01-10-2009, 02:13 AM

We'll just keep it our little secret. But, I'll tell you it drives my SDA's very well and as soon as those Lsi9's get here the first amp they'll be hooked up to is the 545.

As you know I've run LSi 9's as well as my 1C's and have yet to clip the amp, But what do I know. Not saying the NAD is poor choice.........because it's not they are both in the same class.

Oh well, not wanting to turn this into a pity party. Parasound, NAD, Emotiva, Outlaw, Carver, Sunfire, etc; all get the majority of the votes over the lowly and embarrassing Adcom. What do I know...............................I've listened to most of these amps and I still prefer the Adcom by a slight margin. The only amp that I liked better was the Marsh and that was atleast double or more the cost. Again what do I know...........

Wwhen I get my Pass amp..........................Adcom will forever be CRAP :rolleyes::p:rolleyes:

H9

ben62670

01-10-2009, 02:15 AM

I loved my 545. I wish I could have kept that, the 5800, and the 7500 for HT. I won't cry a river though. I am very happy to have my 585, and my 565's mono's especially considering that I paid next to nothing because I know how to repair them:) Some day I want to get my ears on a 5802;)

heiney9

01-10-2009, 02:24 AM

Part of what I said is tongue-n-cheek, but there is some truth there in what I said.

daboyz

01-10-2009, 02:29 AM

heiney9

01-10-2009, 02:34 AM

I've always said..............for 20 years that the 545 is the "gem" of the line. I sold more 545's than the other 2. Again Adcom is not the be all and end all of amps.......but they are a damn fine sounding reliable workhorse inspired by Nelson Pass.

I'm ready to move up the chain but the 545 will stay in office room duty when I do move way up the chain.

H9

P.s. It's late I've had a few and now it's time to stop being such a fanboy.

daboyz

01-10-2009, 02:37 AM

Can I get an Amen and two hallelujahs!!!Thank God the RAS has a clue.

ben62670

01-10-2009, 02:41 AM

Ben, your 545 is my little baby now and I wish that you would stop coveting it, like now!!;) Having both the Marsh and the 545 I've actually come closer to selling the Marsh(except for a mishap;)) than I have the Adcom. I always thought that the Dodd and the Marsh were my two untouchables but I have never even thought of selling the 545.

I'm doing fine over here. I can't afford a full HT system now. The amps I have now are back up to factory spec. Most know about the bad run of leaking caps that plagued the 565's, and the 585's, but there are a few naughty cheap fusible resistors, and a couple caps that will bring the ones I have to a higher level:) Again I have to say thanks H9 for pointing me in the right direction to get some solid advice from the designers, and techs that actually worked on, and built these amps:)
Ben

Dawgfish

01-10-2009, 08:38 AM

Hey Im an Adcom fan. I have a GFA 555 in my system and like it. It's a good amp. I also have an Emotiva amp as well as a Marsh designed Monster Power amp and they all sound good and have their own merits. Sound is a personal thing, what one person likes another may not. There's nothing wrong with Adcom at all (and btw, I have a GFA 545 on the way for my two channel setup), but neither is there anythying wrong with Emotiva also. Don't take it personally. Like what you like and don't worry about the others. It works for me.

sdabeliever

01-10-2009, 09:03 AM

Is that what they call "Power Drive" technology, or is that something different entirely? A fairly recent review of the T955 highlighted this feature, and I'm just curious if it's useful, or if it's useless marketing blurb.

Sorry to derail, slightly, sdabeliever.

I don't know if it's the same or not but I can tell you that from what I've seen so far the NAD is a monster.. it's no marketing blurb when it comes to the NAD.

NAD states that it will easily produce 500 watts per channel in stereo and up to 1.6 Kw in mono. I believe it after hearing the thing.

So, all you late comers... thanks for the comments but can anyone tell me about hooking a transformer into my SDA cable to make an A1? Is it ok to do with my model SDA?

heiney9

01-10-2009, 09:08 AM

I can anyone tell me about hooking a transformer into my SDA cable to make an A1? Is it ok to do with my model SDA?

What model SDA's do you have? Pin/Blade or Blade/Blade SDA cable? Serial Numbers and pics would be great.

In general only the later model SDA's 4th generation (which is the last generation) can use the AI-1 (transformer) cable. But there are some exceptions.

sdabeliever

01-10-2009, 09:51 AM

cool I'll post some pics later. I have sda 2's from 1984

heiney9

01-10-2009, 09:58 AM

cool I'll post some pics later. I have sda 2's from 1984

I can tell you right now that you can't use the AI-1 cable with those. Non-common ground amps weren't really an issue until later on. Still post the pics.

I assume there is no "A" or "B" letter designation. Do yours have external protection fuses? Only the earliest SDA's had these fuses.

Only 2B's with serial numbers on Left greater than 14115 and Right greater than 14124 can use the AI-1 interface.

Look for a common ground amp............that's your only solution. :)

H9

sdabeliever

01-10-2009, 04:57 PM

Uhm yeah. only about 12,000 numbers off :rolleyes: oh well GFA 545 here I come. Anyone want the 2200 for $275 shipped?

THANKS for all the help to all who contributed! This was a good learning experience for me.
http://i250.photobucket.com/albums/gg256/sconeman/SDA%20II/P1050580.jpg
http://i250.photobucket.com/albums/gg256/sconeman/SDA%20II/P1050578.jpg
http://i250.photobucket.com/albums/gg256/sconeman/SDA%20II/P1050576.jpg
http://i250.photobucket.com/albums/gg256/sconeman/SDA%20II/P1050575.jpg

reeltrouble1

01-14-2009, 10:39 AM

DaveMuell

01-14-2009, 10:52 AM

RT1,

Are the 2100 series and the 270 on up also common ground? I have a 2100, 2700, and a 270 and will swap them around if I need to. Currently, the 270 is with the CRS+'s..

ben62670

01-14-2009, 10:55 AM

Those were my first SDA's:) You could have kicked me in the groin when I first listened to them, and that wouldn't have taken the grin off my face:) I was using a GFA-5400 at the time. It had plenty of power, but the GFA-555 sounded better(not just more powerful).
Enjoy.
Ben

reeltrouble1

01-14-2009, 10:59 AM

Dave, I really cant remember as I moved on a few years ago and my NAD fact library has diminished over time, I owned 2600 and 2700 so I am most familiar with those.

RT1

agfrost

01-14-2009, 12:48 PM

Some additional info on NAD amps in this thread: LINK (http://www.polkaudio.com/forums/showthread.php?t=25249)

Jay

heiney9

01-14-2009, 12:56 PM

Last year after patching them up I ty-dyed my 'I Love Adcom" t-shirts and ruined them. I was having a flashback and used to much puprle micro in the mix.

I did order two more but my order was returned as apparently they are no longer available. It seems sales were bad, some guy named Brock did have a long history of 20 years or so of buying them but he only ordered one per year, now I am not saying but they implied he was always calling trying to get something on the down low or a discount, they mentioned another fellow named Ben, who had called looking for a deal on used Adcom T-shirts. They did have a few but sold them on E-bay.

It would be cool to perhaps make a sticky with common ground amp info. for new SDA owners. Some 20 years later this an issue that wasn't necessarily so back then. As for Adcom t-shirts............mine are ruined as well :). That's what happens when you leave them in a drawer for 20 years w/o moth balls to protect them.

Now the Adcom boxers.............that's another story. Those are intact but severely faded. I can still see.......a capital I above the crotch....a red, now pinkish heart squarely on the crotch and ADCOM in big bold letters across my ass. The ladies never dug them but I did.......especially in front of a full length mirror. Ahhhhh those were the days ;).

H9

shack

01-14-2009, 01:21 PM

Are the 2100 series and the 270 on up also common ground?

The NAD C270 and NAD C272 amps (as well as the NAD C370 and NAD C372 integrated amps) are common ground.

reeltrouble1

01-14-2009, 02:02 PM

Now the Adcom boxers.............that's another story. Those are intact but severely faded. I can still see.......a capital I above the crotch....
H9

well it just may of been the ladies believed that "I" stood for Itty bitty........:eek:

RT1--Thanks Shack Daddy.

sdabeliever

01-14-2009, 07:00 PM

Well I'm keeping the NAD for a two channel system we have at our cafe and I just bought a nice 545. I really can't believe that NADs power. wow. We hooked it up to my father in laws sda srs's (without the sda cable) and it sounded better than the onkyo m504 hooked up with the sda cable.

anyway, it would be nice to have that info stickied because I had no clue.

here's a question...My father in law's SDA srs2's have a serial numbers of 2765 and 2865 are these eligible for the A1 cable swap??? we'd like to go dual mono if possible.

sdabeliever

01-14-2009, 07:04 PM

. I was having a flashback and used to much puprle micro in the mix.

RT1

haha:D

reeltrouble1

01-15-2009, 08:25 AM

The SDA speakers that use the pin/blade cable can use mono blocks amplifiers if you use the AI-1 cable, your pretty much going to have to build your own though, there are a couple of threads, Darqueknight (sp) just did a very nice one that looks like the best effort so far, not cheap though.

Keeping the NAD is a good enough decision, it is a nice amp. but watch for a deal on a 2600 or 2700 they are basically the same amp then you can get the SDA and use your speakers as intended.

RT1

RT1

heiney9

01-15-2009, 10:50 AM

Just to add to what Ted's saying not ALL pin/blade (most can though) can use the AI-1 and the OP's SDA's can NOT use the AI-1.

heiney9

01-15-2009, 11:03 AM

here's a question...My father in law's SDA srs2's have a serial numbers of 2765 and 2865 are these eligible for the A1 cable swap??? we'd like to go dual mono if possible.

I'll check the compendium when I get home or maybe Darqueknight can comment. I know Ted already has and he's probably correct especially if they are pin/blade................but there is a serial number run that can for sure use the AI-1.

H9

sdabeliever

01-15-2009, 04:07 PM

that's great thanks!

Leam123

09-19-2010, 01:33 AM

I hope that any of you folks out there that are using or are thinking of purchasing ADCOM eq, have a bottomless pit of MONEY to get them serviced when they fail!!! I have a pair of 8000M's on my bench with wild high freq oscillation problems. I couldn't find ANY service info, manuals or prints for these pups. My customer contacted ADCOM and all he got was useless LIP SERVICE! He was told that he'd have to ship both units from B.C. Canada, to their service dept, in Britan, for repairs. I found the failure, one 4.7 ohm/ 2 watt resistor, in each unit had gone open. I installed 3 watt pwr resistors in their place and both units now spec out as per factory. For a few $$ in parts, I saved my customer a boat load of money. I'm posting this to help others. Nothing burns my wick faster than over priced eq, and then when it comes to service, it's the customer that gets stone walled and the shaft AGAIN! If your ADCOM 8000M sounds like CRAP, I probly have the fix, feel free to email me. Cheers all !